There was no difference in 30 day mortality or major bleeding between the groups:

30 day mortality: 4.9% in the enoxaparin group versus 4.8% in the placebo group (p=0.83)

major bleeding: 0.4% versus 0.3% (p=0.35)

The findings, the authors write, “appear to be counterintuitive, given the fact that pharmacologic prophylaxis has been shown to reduce the risk of venous thromboembolism, including asymptomatic deep-vein thrombosis, by at least 45% in hospitalized, acutely ill medical patients.” But, they write in the conclusion, the results do not mean that thromboprophylaxis is not worthwhile:

Pharmacologic thromboprophylaxis continues to have proven benefits in preventing venous thromboembolism, thus reducing the need for the treatment of symptomatic venous thromboembolism with high doses of anticoagulant agents over a prolonged period of time. Furthermore, venous thromboembolism can lead to nonfatal complications such as the post-thrombotic syndrome and chronic thromboembolic pulmonary hypertension, which are often not treated successfully.